Anti-condensation and Anti-blockage for Heavy Oil Depots: Specialized Solution for Electric Heat Tracing Belts

Liquid caustic soda (sodium hydroxide solution) is prone to crystallization and solidification due to low temperatures in winter, leading to blockages in storage tanks and pipelines. This can also exacerbate equipment corrosion, affecting storage and transportation safety. Electric heat tracing bands, with their advantages of corrosion resistance and precise temperature control, are the preferred solution for heat tracing during liquid caustic soda storage in winter. By scientifically controlling the selection, laying, and operation and maintenance points, a solid operational defense line can be established.

Accurate selection requires adaptation to the characteristics and operating conditions of liquid caustic soda. Liquid caustic soda is highly corrosive, and the heat tracing belt must be made of fluoroplastic or polytetrafluoroethylene sheathing to resist medium erosion and steam corrosion. It is strictly prohibited to use ordinary polyolefin sheathing products. Based on the crystallization temperature of liquid caustic soda (approximately 32°C), a medium-temperature self-regulating heat tracing belt is selected, with a power controlled at 30-40W/m. The power can be adjusted autonomously to maintain a temperature of 35-45°C inside the tank, avoiding local overheating that could lead to deterioration of the liquid caustic soda. In explosion-proof areas, an explosion-proof model of Exd II BT4 or higher grade is required, paired with explosion-proof accessories.

Scientific laying ensures uniform heat tracing throughout the entire area. The tank wall is laid using spiral winding, with a spacing of 25-35cm. The parts with fast heat dissipation such as the tank top, bottom, and discharge outlet are densified to 15-20cm, and are fixed with corrosion-resistant stainless steel ties to ensure the heat tracing belt is tightly fitted to the tank wall. The pipelines are laid in parallel, and irregular parts such as valves and flanges are densely wound. Intermediate junction boxes are set up every 50-80m for sub-loop control, avoiding the impact of single-segment failure on overall heat tracing. An 8%-10% length redundancy is reserved to accommodate thermal expansion and contraction.

The supporting system enhances temperature control and safety protection. Equipped with an intelligent temperature control system, PT100 temperature sensors are installed at different heights in the storage tank to collect temperature data in real time, precisely regulating the start and stop of the tracing band, saving energy while preventing crystallization. The distribution box is selected as an anti-corrosion and explosion-proof model, equipped with a built-in leakage protector and overload protector. For outdoor scenarios, it must meet the IP67 waterproof rating to prevent rain and snow from infiltrating. The insulation layer is made of 50-80mm thick flame-retardant and corrosion-resistant insulation cotton, with seams sealed using anti-corrosion aluminum foil tape. The outer layer is wrapped in waterproof protective cloth to reduce heat loss.

Adhere to installation and operation and maintenance specifications to mitigate risks. Prior to construction, clean the tank walls and pipelines of oil stains and rust to prevent scratching the outer sheath of the heat tracing system. During wiring, use corrosion-resistant sealed connectors, and apply double sealing after the core wires are securely connected to prevent the intrusion of liquid alkali steam. Conduct routine monthly inspections on the sealing status of the heat tracing system's sheath and accessories, and retest the insulation resistance quarterly (ensuring it is ≥20MΩ). Regularly calibrate the temperature control system and promptly replace aging accessories to avoid the combination of corrosion and electrical leakage hazards.

The core of electric heat tracing for liquid caustic soda storage in winter lies in "anti-corrosion adaptation, precise temperature control, and sealing protection". Following guidelines and specifications for operation can effectively prevent liquid caustic soda crystallization and equipment corrosion, ensuring stable storage and transportation. The combination of scientific heat tracing solutions and standardized operation and maintenance is the key to safe and efficient operation of liquid caustic soda storage in winter.